Self-lowering jack



March 1929- s. SELDEN 1,706,710

SELF LOWERfNG JACK Filed June 1, 1925 MW k ATTORNEY.

Patented Mar. 26, 1929 UNITEDFTS'TAVTEIS' PATENT oFFicEq SAMUEL SELDEN, or HUNTINGTON PARK, CALIFORNIA, ssrenon or ONE-HALF TO CHARLES SELDEN, or BALTIIMORIE, MARYLAND.

' SELF-LOWERING'J'ACK.

Application filed June 1, 192 .seriarno. 112,882.

My invention relates to lifting "jacks of the self-lowering type and its main ob ect is to provide a mechanism of very simple but highly practical and efficient construc tion by which the operation of the ac k either in lifting orin lowering a load is readily controlled. I

Another object of the invention is to provide in a self-lowering jack, a controlling mechanism that may be governed by means of the same lever used in operating the jack to lift the lead. A further object is to provide a controlling mechanism having a powerful and dependable restraining action upon the lifting screw of the j ack'so as to positively prevent breakage or accidental yielding under heavy pressure and still another object is to provide a controlling mechanism of the above stated characteristics which is applicable to lifting acks of both the ver tical and inverted types. I

Tith the above and other obj ects in view,

will fully appear in tliecour'se of the following description, my invention consists in' the constructlon, arrangement and comb1- J nations of parts shown in the accompanying drawing.

The drawing illustrates a preferred embodiment of the invention but it is to be understood that changes in the specific con-Q I I I I I scribed, and lt 1s closed by a screw plug 14 provided with a grooved wear-plate 15 struction and the general arrangement of the parts may be made without departing from the spirit of the invention as defined in the hereunto appended claims. 1

The drawings show the embodimentof the invention in association with a lifting jack of the vertical type and it will be evident to those versed inthe art that it isjlikewise applicable to jacks of the inverted? type without material changes in the arrangement of the parts included in the invention. I I I In the drawings in the several views of which like parts are similarly designated, I

Figure 1, represents a sectional elevation of a vertical lifting jack to which my invention has been applied, I a I Figure 2, asection in a horizontal plane taken on the line 22 Figure 1;

Figure 3, an enlarged fragmentary section along the line 33 Figure 2;

' Figure 4:, an' enlarged fragmentary section in a vertical plane on the line 44 Fig ure 2; and" V The lower flange'of Figure 5, a section taken on the line 55 Figure 4:. I

Referring further to the drawings, the

reference numeral 5 designates the standard of the lifting jack, supported on a foot plate 6 and provided' at its upper end with a fixed nut 7'. The standard is hollow to admit the lower portionof the lifting screw 8 which cooperates with the nut to lift the load by rotation about its vertical axis;

The threads of both the screw and the nut are, as is usual'in jacks of the self-lowering type, coarse and steeply pitched to compel the screw to'move downwardly under the influence of its load when it isreleased by the restraining applianceto which the present invention particularly appertains.

The screw-stem 8 carries at its upper ex I trernity in fixed relation thereto, a beveled gear wheel 9, the upper'portion ofwhich comprises a grooved wear-plate 10 forming the lower member of a ball-bearing 12 which supports the lifting shell 13 of the 'ack. I

This lifting shell, the major portion of which is slidably fitted upon the standard,

hasatits upper end, above the standard, an

enlarged chamber for the operating and controlllng mechanisms hereinafter to be dewhich constitutes the upper member of the I ball-bearing hereinbefore referred to.

A pinion 16 on a shaft 17"supported in a bearing on. the lifting shell, meshes with the gearwheel 9, and the shaft carries outside of the'shell, the usual ratchet 18, for its operative connection with a socket-piece 19 into which, in practice, the operating lever wheel is a relatively loosebrake drum 21. of

channel section which is supported on a bearing surface of the gear wheel below the ratchet wheel. I I

I I the brake-drum fits upon the hub of the gearwheel, and its upper flange projects to the upper? edge of the ratchet wheel.

Pivotally mounted in the fchannel of the brake-drum, are a plurality of pawls 22 of lowering the load.

are disposed in a recess of the lifting shell to hold the hand against rotation.

The sections of the band have at their free ends opposed lugs QGengaged by helical springs 27 which at their outer ends bear upon shoulders 28 of the lifting shell.

Between the lugs of the brake-band is arranged a cam 29 on a shaft- 30 which is rot-atably supported in a bearing of the lifting shell.

The shaft carries upon its portion exteriorly of the shell, a socket piece 81 similar in part to that associated with the pinion shaft 17. A boss 32 on the lifting shell supports the hinge-portion oi the brake-banrjl and a similar, boss 33 aids in supporting the lugs 26 and the springs 27.

Having thus described my invention, its operation .is as follows:

A load superimposed upon the littin shell is raised by an oscillatory movement of a lever inserted in the socket 19, which thru the medium of the ratchet 18, imparts an intermittent rotary motionto the pinion 16.

The pinion rotates the gear-wheel 9 which thereby causes the screw to turn in the relatively stationary nut 7. The consequent upward movement of the screw communicated through the medium of the ball bearing to the lifting shell, raises the load.

During this entire operation, the brake drum is held against rotation by the gripping action of the brake band under the intiuence of the springs 27 and the pawls on the inside of the druin'ride freely across the teeth of the ratchet wheel. a

It will be apparent that retrograde motion of thefscrew by the weight of the load on the lifting; shell is constantly opposed by the pawls on the relatively fixed. brake-drum and that only when thedr'um is released to turn with the ratchet wheel, the screw is permitted to move downwardly for the purpose 'lhis'object is'attained by moving the free ends of the brake-band further apart agaii'ist the pressure of the springs 27, which may be accomplished by a partial rotation oi? the cam through theinedi.um of a lever inserted in the socket3i.

When the brake-drum .is thus released, leaving it free to rotate with the beveled gear wheel, the weight of the load on the lifting shell will compel it to move downwardly owing to the steep pitch of the thread on the screw. The downward motion of the load is under constant control of the operator who by proper manipulation of the lever can at any time stop the movement of the operating mechanism by moving the cam to its normal position in which the brake drum is tightly gripped by the spring-pressed brake band.

The same lever may be used in lifting and in lowering the load and both operations are readily accomplished without any adjustment other than moving the lever from one socket to the other. I

Having thus described my invention what I claim and desire to secure by Letters Patent is v i 1. A Self-lOWGllIlg lifting jack comprising a stationary element, a relatively movable element, mechanism for the operative move ment of the latter, including a rotary gear member, a ratchet wheel on the gear member, a rotary brake-drum, a pawl on the drum cooperative with the ratchetwheel, to establish the rotative continuity of the drum and the gear member in one direction only, a spring-urged brake-band adapted to restrain the rotary movement of the drum by frictional cont-act therewith, a rotary cam controlling the action of the brake-band upon the drum, and a. lever socket connected with the cam for its rotary adjustment by a lever inserted in the socket. i p v 2. A self-lowering lifting jack comprising a stationary element, a relatively movable element, mechanism for the'operative movement of the latter, including a rotary gear member, a ratchetwheel on the gear member, a rotary brake-drum of channel section,

'p'awls in the channel of the brake drum, co-

operating with the ratchet wheel to establish the rotative continuity of the drum andthe gear member in one direction only, a

spring-m'ged brake band adapted to restrain the rotary movement of the drum by frie tional contact therewith, and adjustable means to Conn-o1 the action of the brake band upon thedruin. i Z

3. itself-lowering lifting jack comprising a stationary element, a iQllitl'VBlYdnOVztblC element, mechanism for the operative inovement of the latter, including a rotary gear member, a ratchet heel on the gear member,

. a rotary brake drum of channel section, bolts extending between the sides of the channel of the brake drum, pawls pivoted onv the bolts, cooj ieratin g with the ratchet wheel to establish the r'otative continuity of the drum and the gear member in one directiononly, a spring-urged brake band adapted to restrain the rotary movement of the drum by frictional contact therewith, and 'adjiistable means to control the action of the brake band upon the drum.

In testimony whereof I have hereunto affixed my signature. p, SAMUEL SELDEN. 

